The Specialized Roubaix

When Specialized introduced the Roubaix in 2004, it was the first bike on the market to combine top-of-the-line carbon fiber construction with a more relaxed geometry aimed at riders doing charity rides and centuries. Up to this point in time, the handful of bikes out there from the bigger manufacturers that combined a longer head tube for higher handlebar position, a longer than usual wheelbase and more trail for greater stability were made from aluminum and were rarely equipped with anything as nice as Shimano 105.

The implicit message seemed to be that if you weren’t fast you wouldn’t appreciate quality. The reality was simpler: For companies like Giant and Specialized, these early bikes had been aimed at a new wave of cyclists entering the sport, often as a result of events like the AIDS Ride. Getting these riders transitioned to a road bike from a mountain bike had been a significant achievement and there was little stomach on the part of risk-averse product managers to try to steer them into a bike 10 times as expensive as their last.

The road product development team recognized a need for a bike that combined the geometry found in the charity ride bikes with the high performance carbon fiber technology found in their top-of-the-line Tarmac. The Roubaix has been an unqualified hit among more than just the charity ride crowd.

The chicane in the chainstays really doesn’t flex much vertically, but aids in vibration damping

So how different is the Roubaix from the Tarmac? On paper, the differences seem minor, insignificant even. Just a few millimeters here, a centimeter or two there. Let’s compare a 56 in each:

Tarmac

Roubaix

Seat tube length

53cm

51.5cm

Top tube length

56.5cm

56.5cm

BB Drop

69mm

71.5mm

Chainstay length

40.5cm

41.5cm

Seat tube angle

73.25 degrees

73.25 degrees

Head tube angle

73.5 degrees

72.5 degrees

Fork rake

43mm

49mm

Trail

56mm

56mm

Front center

59.3cm

60.6cm

Wheelbase

98.8cm

101cm

Standover height

80cm

80.1cm

Head tube length

17cm

19cm

Three dimensions are the big determiners for fit: the top tube length, the seat tube angle and the head tube length. Those first two—top tube length and seat tube angle are identical. What changes is the head tube length; its greater length gives riders the opportunity to adopt a bar position 2cm higher, allowing them to sit more upright without exposing too much fork steerer above the top headset bearing. As many of you are already aware, too much exposed steerer is at risk for breaking because of the greater leverage the rider can exert on the steerer from the handlebar.

So the bike offered a less aggressive position for greater comfort. The designers didn’t stop there. They increased the wheelbase length by more than 2cm by increasing the chainstay length and by using a slacker head tube angle and more fork rake, thereby increasing the front center distance as well. Practically speaking, this increased the distance between the rider and the wheels, cutting road vibration. More comfort.

The choice to go with a longer wheelbase had an added benefit. It addressed the rider’s more upright position and higher center of gravity (CG) which resulted in reduced weight on the front wheel (relative to the weight distribution in the Tarmac). Bottom bracket drop was also increased to help offset the higher CG; 2.5mm may not seem like much, but it’s enough to make a subtly helpful difference.

The Zertz inserts in the fork are angled to absorb more vibration

The longer wheelbase of the Roubaix means the bike won’t track quite as tight a turn as the Tarmac, but the fact that the slacker head tube angle is paired with more fork rake results in exactly the same trail as the Tarmac. As a result, steering input remains as crisp as the Tarmac’s.

Back to the issue of comfort. The Roubaix’s single most distinctive feature are the Zertz inserts in the fork, seatstays and seatpost. The size of those inserts and the way they are positioned in the fork and seatstays has changed since the Roubaix was first introduced in 2004. They are larger now and positioned more at an angle to the fork blades and seatstays to better serve their purpose, which is to interrupt the transmission of vibration.

I’ve met riders who doubt the Zertz inserts do what they are advertised to accomplish. Having ridden the Roubaix (in various iterations) more than 1000 miles and having ridden other, grand touring category bikes, I do believe that the Zertz inserts cut vibration transmitted through the frame. I often compare vibration—which is different from road shock—with the vibration from a lawnmower. While it’s not nearly as severe, I think the point illustrates the issue rather well. Anyone who has ever used a lawnmower with a two-stroke engine (as opposed to a push mower or an electric mower) knows well the interesting feeling your hands have once you let go of the mower. For a minute or more afterward your hands feel, well, like they are still on the mower. Sex aids wish they were so memorable.

6 comments

Using a scale what was your weight distribution on the Roubaix vs. the Tarmac (same stem length, et al)? That would be interesting.

Much like you previous articles on geometries, weight, etc… something I have thought about for years. Seems like for a given size of frame a manufacturer should specify an ideal stem length/angle (or a point is space where the stem meets the bars) to give the proper leverage and weight distribution when steering.

Or something… 😉 And what is the ideal weight distribution between front and back (while I’m asking) on a road bike?

And when I make chocolate milk, how can I get those little floating balls of chocolate to NOT form?

Actually, headtube length is irrelevant without considering other variables.

Assuming that the bottom of the headtube is the same distance from the ground (with a different HTA, and different fork, its hard to be sure), and the 2.5mm difference in BB drop, the effective difference in handlebar height is 4.5mm or close to an inch. And that’s 2X what is suggested in the post.

Rick G: You bring up a fair point. While the fork lengths are different between the Tarmac and Roubaix, the height of the upper bearing from the ground is but 2cm different. However, when you consider the spacers used on each bike (5cm for the Roubaix, 3cm for the Tarmac) the difference in bar height for the delivered bikes is a total of 4cm.

Souleur: I chalk the difference in BB drop up to the anticipated likely difference in bar height. It’s an effort to try to shift the CG back down just a touch.

It seems like the opposite design philosophy happens on the lower end bikes. If you can’t afford a top end bike, you don’t need a pure racing machine. I would rather have (and do have) a stable of $2,000 bikes than one $10,000 one. The only exception I have found to the above rule so far is Masi, who offers the 3vc as a frame and four different builds (105 to team).